| In order to improve the utilization rate of timber,many scholars proposed to replace solid columns with glulam hollow columns as load-bearing members,but the current research mainly focuses on axially compressed members,and the force performance under eccentric compression,especially large eccentric compression,is not clear.Therefore,in order to explore the eccentric compressive performance of glulam hollow columns,this paper investigates the damage mode,damage mechanism,bearing capacity,load-strain relationship and load-deflection relationship of glulam hollow columns by conducting one-way eccentric compressive bearing tests on seven groups of specimens with different eccentric distances,and compares the bearing capacity of eccentric compressive columns with that of axial compressive columns.At the same time,the finite element analysis software is used to establish the calculation model for simulation analysis.Finally,the bearing capacity calculation results of relevant formulas of national timber structure codes are compared with the test results,and the eccentric pressure generated bending moment is increased by considering the lateral deflection in the column,and the eccentric compression bearing capacity calculation method of glulam hollow columns is proposed.The main research results of this paper are as follows:(1)Through the test,the damage mode,bearing capacity and deformation law of the eccentrically compressed glulam column are revealed,and the eccentricity of the hollow column is about 0.6 for the limit of dimension eccentric.The small eccentrically compressed specimen is generally bending concave side(compressed side)yielding or cracking,while the bending convex side(tensile side)is basically not damaged,and the large eccentrically compressed specimen is firstly bending concave side yielding,and then bending convex side is pulled off.Large eccentric compressive damage and small eccentric compressive damage is obviously different:the bending convex side has obvious damage phenomenon,and the damage is relatively sudden;the specimen bearing capacity is rapidly reduced,and the deflection deformation is larger.As the eccentricity increases,the bearing capacity of the specimen gradually decreases.For specimens with an eccentricity of 30mm to 100mm,their ultimate bearing capacity decreases to 61.51%to 31.16%of the bearing capacity of the axially compressed specimen,respectively.At the same time,the slope of the load-eccentricity curve slows down,that is,the declining range decreases.From the load strain relationship curve,it can be seen that hollow glulam columns have a certain plastic deformation capacity.(2)The bearing capacity calculated through the finite element model is basically consistent with the experimental values,and although the calculated deflection has some error with the experimental values,it is also within a reasonable range When the model established in this paper is loaded to the ultimate bearing capacity,the bending concave side will reach the compressive strength,which is consistent with the test phenomenon that the bending concave side of the specimen is yielded.(3)Through comparative analysis of national codes,it can be seen that the U.S.National Design Standards for Wood Construction NDS一2018 of the United States is more accurate in the case of small eccentric compression,but the theoretical calculation value of the Technical code of glued laminated timber structures GB/T 50708-2012 is generally closer to the test average value.Based on the Standard for design of wood structures GB 50005-2017,this paper proposes a calculation method on the bearing capacity of eccentrically compressed glulam hollow columns The error between the theoretical value and the test average value is less than 10%,with high accuracy,which can provide theoretical reference for engineering design. |
